The PC/ABS blends described in JP-A 11-199768 are made flame-retardant by the inclusion of monomeric and oligomeric phosphoric esters. The flame resistance is distinctly improved by the addition of inorganic filler such as talc. However, the reduction in the phosphate content that may be accomplished by such addition while retaining flame resistance, is insufficient to obtain the melt viscosities that are necessary for extrusion applications. Furthermore, the inorganic filler generally has an adverse effect on the mechanical properties, in particular on the toughness of the polycarbonate blend.
U.S. Pat. No. 5,849,827 and WO 99/07782 describe PC/ABS molding compositions that have been made flame-retardant with resorcinol-based or bisphenol-A-based oligophosphate, the burning-times being distinctly reduced by addition of nanoscale inorganic materials in low concentrations. Lacking in melt stability these compositions are unsuitable for extrusion applications.
WO 99/57198 describes PC/ABS molding compositions that have been made flame-retardant with a resorcinol-derived oligophosphate and that are distinguished by a very low Teflon content of only 0.1 wt. %, corresponding to a fluorine content of 0.076%. Linear and branched polycarbonates with a high molecular weight (31,000 g/mol or 32,000 g/mol) find application in the molding compositions. While their rheological properties make them extrudable these compositions exhibit poor ESC behavior and inferior thermal stability, particularly in the instances where sufficient flameproofing agent is incorporated to achieve a sufficient flame resistance and applications entailing thin wall thicknesses.
US 2002/0077417 A1 disclosed flame-retardant polycarbonate resin compositions consisting of branched polycarbonate, a silicone/acrylate composite graft polymer, oligomeric phosphoric ester, polytetrafluoroethylene and, optionally, talc. Oligomeric phosphoric esters of the BDP type are not disclosed.
WO 02/100948 A1 discloses thermoplastic molding compositions containing branched polycarbonate, graft polymer, talc with a mean particle size below 1000 nm and optionally, oligophosphates, vinyl copolymers and anti-dripping agents. WO 01/48074 A1 discloses thermoplastic molding compositions containing branched polycarbonate, graft polymer, talc having a special purity and optionally, oligophosphates, vinyl copolymers and anti-dripping agents.
EP 0 675 001 A1 discloses compositions containing a thermoplastic resin (such as polycarbonate, for example) and water-eliminating compounds, (e.g. zinc borate) wherein phosphorus-containing flameproofing agents, talc, acrylonitrile-butadiene-styrene copolymer (ABS) and styrene-acrylonitrile copolymer (SAN) may optionally be included as further components. These resin compositions are suitable for marking by laser.